mlx4_ib_query_ah
mlx4_ib_query_ah(&ah.ibah, &ah_attr);
.query_ah = mlx4_ib_query_ah,
mlx4_ib_query_ah(dev->sm_ah[ctx->port - 1], &ah_attr);
int mlx4_ib_query_ah(struct ib_ah *ibah, struct rdma_ah_attr *ah_attr);